Time- and dose-dependent toxicity profiles and molecular correspondence of nanoplastics in human embryonic stem cells (H9)

, from 172.6 μg/mL at 24 h to 37.93 μg/mL at 48 h, and further to 11.25 μg/mL at 72 h. Flow cytometry and confocal imaging revealed that PS could be effectively internalized, with uptake increasing from 2.5% at 5 μg/mL to 77.65% at 100 μg/mL after 24 h, and approaching 84% after 72 h. All NPs increased intracellular reactive oxygen species with PS-induced responses being the strongest, reaching 14.6-fold and 22.8-fold higher than the control group at concentrations of 50 and 100 μg/mL, respectively. Western blot analysis showed that caspase-3 remained largely unchanged, while Oct-4 levels increased and p-p38 levels decreased, especially under PVC exposure. Pharmacological inhibition of p38 MAPK only resulted in a slight increase in Oct-4 levels, indicating that the weakened p38 signaling pathway plays a limited role in PVC-related molecular responses. RT-qPCR further showed that Nanog was significantly upregulated at concentrations of 50 and 100 μg/mL under PVC exposure, and Sox2 was significantly upregulated at a concentration of 100 μg/mL. These findings reveal the potential mechanism by which nanoparticles induce hESC toxicity and provide a scientific basis for assessing their developmental risk.